1. Field of the Invention
The present invention generally relates to a method for forming a semiconductor device, and more particularly to a method for inspecting a pattern defect process.
2. Description of the Prior Art
Referring to FIG. 1, firstly, a substrate 100 is provided. The substrate 100 comprises silicon. The polysilicon layer 102 is formed on the substrate 100. The thickness of the polysilicon layer 102 is between about 3000 and 8000 angstroms. The polysilicon layer 102 is etched anisotropically to define gates 102a, 102b, and 102c. The sides of gates 102b and 102c have defects 103a and 103b. The thickness of defects 103a and 103b is about 1000 angstroms. It""s very difficult to inspect defects 103a and 103b on side of gates 102a and 102b by visible light because the thickness of gates 102b and 102c is higher than and the defects 103a and 103b. Defect inspection is an important issue in a semiconductor fabrication.
For the foregoing reasons, there is a necessary for a method for inspecting a pattern defect process.
In accordance with the present invention, a method is provided for inspecting a pattern defect process that substantially can easily measure signal-to-noise ratio of defects on the substrate.
One object of the present invention is to provide a method for inspecting defect sensitivity process that can easily measure signal-to-noise ratio of defects on the substrate.
In order to achieve the above objects, the present invention provides a method for inspecting a pattern defect process, in which a layer is formed to raise signal-to-noise ratio on a substrate. This invention also provides a method for inspecting a pattern defect process. First of all, a substrate is provided. Then, a device profile is formed on the substrate, wherein the device profile comprises a defect portion. Then, a layer is formed on the device profile and the substrate, wherein the layer has an etch selectivity different from the etch selectivity of the device.. Next, the layer is removed partially to stop on the device profile and to cause a revere mask. Then, the device profile is etched on the substrate by using the revere mask as a mask. Finally, the revere mask is removed.